The first clear view of a boiling cauldron where stars are born

The RCW49 galaxy nebula in the photo above is one of the brightest star-forming regions in the Milky Way. By analyzing the movement of carbon atoms in the expanding gas bubbles surrounding the Westerland 2 cluster in RCW 49, UMD-led research teams have seen the clearest stellar wind-driven bubbles ever that give rise to stars. I created an image. Credits: NASA / JPL-Caltec / E. Churchwell (University of Wisconsin).

Researchers at the University of Maryland created the first high-resolution images of hot plasma and expanding bubbles of ionized gas where the stars are born. Earlier low-resolution images did not clearly show the bubbles and did not see how the bubbles expanded into the surrounding gas.

Researchers used data collected by the Stratospheric Observatory of Infrared Sciences (SOFIA) telescope to analyze one of the brightest and largest star-forming regions of the Milky Way galaxy. Their analysis showed that a single expanding bubble of warm gas surrounds Westerland 2. Star cluster And it disproved previous research suggesting that there may be two bubbles around Westerland 2. Researchers have also identified the source of bubbles and the energy that drives their expansion.Their results were posted in Astrophysical Journal June 23, 2021.

“when Giant star Shapes, they blow off much stronger emissions of protons, electrons, and heavy metal atoms compared to our sun, “said Maitraiyee Tiwari, a postdoctoral fellow at the UMD Faculty of Astronomy. Stellar wind, And extreme stellar winds can be shaped by blowing bubbles in the clouds around cold, dense gases. We were able to observe such bubbles centered on the brightest clusters in this region of the galaxy and measure their radius, mass, and rate of expansion. “

The surface of these expanding bubbles is made of a high-density gas of ionized carbon, forming a kind of outer surface. shell Around the bubbles. It is believed that new stars are formed within these shells. However, like boiling cauldron soup, the bubbles surrounding these clusters overlap and mix with the surrounding gas clouds, making it difficult to distinguish the surface of individual bubbles.

Tiwali and her colleagues created a clearer image of the bubbles surrounding Westerland 2 by measuring the radiation emitted by the cluster over the entire electromagnetic spectrum from high-energy X-rays to low-energy radio waves. Previous studies using only radio and submillimeter wavelength data produced low resolution images and did not show bubbles. Among the most important measurements was the far-infrared wavelength emitted by certain carbon ions in the shell.

The first clear view of a boiling cauldron where stars are born

A team led by a UMD astronomer uses data from NASA’s SOFIA telescope on board a significantly modified 747 jet, as seen in this artist’s rendering, to create a star-bearing stellar gas expanding bubble. Created the first crisp image of.Credit: Artist Rendering by Marc Pound / UMD

“Using spectroscopy, we can actually see how fast this carbon moves in and out of us,” said PhD Ramsey Karim (MS ’19, Astronomy). A student of UMD astronomy and a co-author of research. “This technique uses the Doppler effect, which is the same effect that the pitch changes as the train horn passes. In this case, the color changes slightly depending on the speed of the carbon ions.”

Tiwali and Karim surround Westerland 2 by determining whether carbon ions are moving towards or away from Earth and combining that information with measurements from the rest of the electromagnetic spectrum. You have created a 3D view of the expanding stellar-wind bubble.

In addition to finding a single stellar-driven bubble around Westerlund 2, they found evidence of new stars forming in the shell region of this bubble. Their analysis also suggests that as the bubbles expanded, they broke on one side, emitting hot plasma and slowing the expansion of the shell about a million years ago. But then, about 200,000 or 300,000 years ago, another bright star in Westerland 2 evolved, and its energy reactivated the expansion of the Westerland 2 shell.

“The expansion of the bubbles surrounding Westerland 2 was accelerated again by the wind from another very large star, which restarted the process of expansion and star formation from the beginning,” Tiwali said. “This suggests that stars will continue to be born in this shell for a long time, but as this process progresses, they will become newer. Performer It will be bigger and bigger. “

Tiwali and her colleagues will apply their method to other bright clusters and warm bubbles to better understand these star-forming regions of the galaxy. This work is part of a multi-year program supported by NASA called FEEDBACK.

For more information:
“SOFIA Feedback Survey: RCW49 Stellar Wind Driven Shell Dynamics Survey” Astrophysical Journal (2021). DOI: 10.3847 / 1538-4357 / abf6ce

Quote: The first clear view of the boiling cauldron where the stars are born (June 23, 2021) is from 6 of 2021 Obtained on June 23

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The first clear view of a boiling cauldron where stars are born

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